When graphed for color and luminosity, most stars fall inside a set of well-defined bands, the largest of which is called the main sequence. Main sequence stars, from hottest/largest to coolest/smallest, are class O, B, A, F, G, K, M, which can be remembered with the mnemonic "Oh, be a fine girl, kiss me!" There are other classes of stars, but they are less common than the main sequence stars. For reference, our sun is a main sequence G2 star.<BR><BR>Info on methods by which stars are named.